Manufactured homes need adequate roof ventilation to keep the airflow circulatning well and temperature regulated, as well as comfortable within the home. This also prevents the moisture buildup that can lead to mold, mildew and structural damage. The type of ventilation system to implement is highly dependent on the build of your home and roof material, slope and overhang width. Other vents on the roof also facilitate proper function of your plumbing systems.
According to the Department of Housing and Urban Development (HUD) Code, attics and roof cavities shall be vented with at least one of the following: (1)
- A minimum free ventilation area of not less than 1/300 of the attic or roof cavity floor area. At least 50% of the required free ventilation area shall be provided by ventilators in the upper portion of the space to be ventilated. Minimum 40% shall be provided by eave, soffit or low gable vents. The location and spacing of vent openings and ventilators shall provide cross-ventilation to the entire attic or roof cavity space. A clear air passage space having a minimum height of 1 inch shall be provided between the top of the insulation and the roof sheathing/covering.
- A mechanical attic/roof ventilation system may be installed instead with the system providing a minimum air change rate of 0.02 cubic feet per minute, with intake and exhaust vents located to provide air movement.
The only exception to these ventilated roofs are single wide manufactured homes with metal roofs having no sheathing or underlayment. More of the specifics of that exemption in the HUD Code you can find here: https://www.huduser.gov/publications/pdf/attic_ventilation.pdf
Know Your Vents
Ridge vents are the most common and are found where your two roof planes meet, also known as your “ridge.” This is often the tip of the roof, covered by a “ridge cap.” These vents are exhaust vents meant to release warm, moist air, in effect making your home cooler. They are made of a molded plastic copolymer that can withstand high-impact. (2)
Note that ridge vents can only be used if your home’s width, length of eaves or overhang, roofing material meet its requirements. The biggest consideration is the roof slope must be of a 3:12 pitch or more (often found in double wide homes). (3)
Ridge vents are great in circulating airflow 24/7, without any electricity, all while having no water or snow enter your home! (4)
Since the Manufactured Housing Construction and Safety Standards (MHCSS) require all roof cavities be ventilated, manufactured homes (commonly single wide models) with less of a soffit venting and no roof overhangs can opt for a roof box vent instead. Vents are important to help regulate the temperature and airflow in your home as well as give better insulation and therefore energy efficiency! (3)
Another vent going up through the roof are your vent pipes, connected to each drain. These are meant to facilitate the movement of water in your plumbing, stopping any siphonage from happening. (2)
Throughout all of this, it’s always best to consult a professional first on the type of vent suitable for your home. They will also take into account the spacing between rafters in installation is possible. Installing your vents may also entail more soffits to make these vents effective, which in turn are dependent on wall thickness, eave width and the humidity of your climate.(3)
Roof ventilation helps your manufactured home stay cool in the summer months, drawing the hot air out of your space. This reduces discomfort and increases energy efficiency in your home! For those that live in cooler climates, ridge vents can also lessen ice dams. (3)
Energy efficiency is a great benefit for manufactured homes as older models suffer from energy inefficiency, leading to higher electricity bills. Ventilating your attic is important as this also prevents the extremely high moisture buildup that can lead to mold, mildew or damage the roof structure. (4)
Lastly, don’t leave out having adequate insulation installed for your roof! Thermal insulation is the first layer of protection of thermal transfer between your living space and roof cavity. (4)
References
- Manufactured Housing Research Alliance . (2002, October 21). Attic ventilation design strategies for manufactured homes. U.S. Department of Housing and Urban Development . Retrieved June 2022, from https://www.huduser.gov/publications/pdf/attic_ventilation.pdf
- Admin. (2019, November 23). Why do mobile homes have vents above the doors? Quick. Retrieved June 2022, from https://quick-advices.com/why-do-mobile-homes-have-vents-above-the-doors/
- Miles, H. (2021, December 22). Ridge vents on manufactured homes (7 things to know). Home Inspection Insider. Retrieved June 2022, from https://homeinspectioninsider.com/ridge-vents-on-manufactured-homes-7-things-to-know/
- Stevens, S. (2021, January 17). Do manufactured Homes Need Ridge Vents? (here are twelve reasons why you should get them). Manufactured Home Parts And Accessories. Retrieved June 2022, from https://manufacturedhomepartsandaccessories.com/manufactured-home-ridge-vents/
